Preparation, structural characterization and thermal decomposition mechanism of [Cu(TO)₂(H₂O)₄](PA)₂

[Cu(TO)₂(H₂O)₄](PA)₂ was prepared by the reaction of aqueous 1,2,4-triazol-5-one (TO) solution with the solution of copper picrate Cu(PA)₂ and characterized by elemental analysis, FT IR and X-ray powder diffraction analysis. The title complex has been studied by means of TG-DTG and DSC under conditions of linear temperature increase. The thermal decomposition residues were examined by FT IR analysis. Thermal decomposition mechanism of the title complex was proposed. In the temperature range of 30-680°C, the thermal decomposition process was composed of four major stages. The first stage was an endothermic process with the loss of four coordination water molecules. Since the dehydration product was unstable, when it was heated, it would be decomposed much more easily. The second stage was composed of an acute endothermic process and a continued strong exothermic process and the main decomposed residues were CuCO₃, Cu(NCO)₂ and polymers during this stage. The third stage was a sharp exothermic process, which resulted from the decomposition of the polymer. After the forth stage, the final decomposed residues were certainly copper oxide. The Arrhenius parameters have been also studied on the dehydration process and the first-step exothermic decomposition of [Cu(TO)₂(H₂O) ₄](PA)₂ using Kissinger's method and Ozawa-Doyle's method. The results using both methods were consistent with each other. The Arrhenius equation can be expressed as ln k=24.0-179.8×10³/RT for the dehydration process and ln k=16.7-206.0×10³/RT for the first-step exothermic decomposition, on the basis of the average of E _a and ln A through the two methods.